RE: [ts-7000] Re: Frame Buffer Programming - Excellent book on graphics programming

["William C. Landolina" <>]

I highly recommend:

Computer Graphics: Principles and Practice in C (2nd Edition)
(Hardcover) 
by James D. Foley, Andries van Dam, Steven K. Feiner, John F. Hughes

http://www.amazon.com/gp/product/0201848406/sr=1-5/qid=1156365643/ref=sr
_1_5/104-9508715-9934366?ie=UTF8&s=books

[New and used from $25...]

The basic things you might want to search the web for are Bresenham's
line and circle algorithms.  After that, you'll probably want to find C
source for "Bezier Splines" when you want to make things besides lines,
circles, and simple geometric figures.

Enjoy,
Bill.

-----Original Message-----
From:   On Behalf
Of PeterElliot
Sent: Tuesday, August 22, 2006 7:37 PM
To: 
Subject: [ts-7000] Re: Frame Buffer Programming ? Solved - example
circle drawing program

Hi Eduardo,

Here's my current circle routine. I haven't optimized the 
circlePlotPoints function as yet.. I can't remember where I found the 
basic routine, but if I do I'll give them credit when I create my 
library...

#define VGAxy(x,y) ((y<<9)+(y<<7)+x)
void circleMidpoint(int xCenter, int yCenter, int radius, int color);

void circleMidpoint(int xCenter, int yCenter, int radius, int color) {
  int x = 0;
  int y = radius;
  int p = 1 - radius;
  void circlePlotPoints(int xCenter, int yCenter, int x, int y,int 
color);

  /* Plot first set of points */
  circlePlotPoints(xCenter, yCenter, x, y, color);

  while (x < y) {
    x++;
    if (p<0) p+=(x << 1)+1;
    else { y--; p += ((x-y)<<1) + 1; }
    circlePlotPoints(xCenter, yCenter, x, y, color);
  }
}

void circlePlotPoints(int xCenter, int yCenter, int x, int y, int 
color){
  int Adr,x2,y2;

  x2=(x<<1);
  y2=(y<<1);
  Adr=VGAxy((xCenter-x),(yCenter-y));                   // Initial pair
  fb[Adr]=color;
  Adr+=x2;
  fb[Adr]=color;
  Adr=VGAxy((xCenter-x),(yCenter+y));                   // 2nd pair
  fb[Adr]=color;
  Adr+=x2;
  fb[Adr]=color;
  Adr=VGAxy((xCenter-y),(yCenter-x));                   // 3rd pair
  fb[Adr]=color;
  Adr+=y2;
  fb[Adr]=color;
  Adr=VGAxy((xCenter-y),(yCenter+x));                   // 4th pair
  fb[Adr]=color;
  Adr+=y2;
  fb[Adr]=color;

  /* 
    I'm looking to calculate the center point address
    (AdrBase = VGAxy(xCenter,yCenter)) and the (x*640)
    and(y*640) and then add/subtract them along with
    x/y to the base address as needed.
  */
}

Hope this works out for you.

Regards,

PJE

--- In  "Eduardo Mendiola" <> 
wrote:
>
> Do you know where I can get a copy of the circle drawing program?
> 
> Thanks, Eduardo
> 





 
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